Estimating design hydrographs at the basin scale: from event-based to continuous hydrological simulation

Abstract

Design hydrographs are widely used in practical hydrologic engineering problems. Typical applications adopt event-based (EBM) methods, using rainfall-runoff models to convert design hyetographs into design hydrographs. Uncertainties include the definition of antecedent conditions and the assumption of equivalence between hyetograph and hydrograph return periods. An alternative is to use continuous simulation (CSM) methods, by forcing a rainfall-runoff model with long precipitation series, and directly analyzing the output discharges. To better understand uncertainties in the EBM method and differences between CSM and EBM ones, we applied a hydrological model in the Itajaí-Açu river basin to compare a CSM method with 730 different simulations of an EBM one, considering different basin antecedent conditions and design hyetographs (10- and 50-years). Results indicated that the EBM method leads to a large range of design discharges depending on the antecedent condition. CS-based 10- and 50-years maximum discharges corresponded to percentiles between 30% and 50% of the EBM estimates. Higher discharge variation occurred in sub-basins with larger maximum soil water storage. Our conclusions agree with the literature, which points towards CSM-based methods to estimate design discharges.

Impact of climate change on the flow of the Doce River basin

“…The MGB hydrological model was chosen for this study because it presents good results in the representation of hydrological processes on a large scale (Paz et al, 2013;Lopes et al, 2018;Siqueira et al, 2018;Fleischmann et al, 2019) and has been applied to assess the impacts of climate change on water resources in several studies in large river basins in Brazil (Queiroz et al, 2016;Schuster et al, 2020) and South America (Brêda et al2020).…”

Fully coupled hydrological–hydrodynamic modeling of a basin–river–lake transboundary system in Southern South America

“…The water levels of the CSG were provided by the Port of Pelotas, which has a ruler installed next to the pier. It was first used in large basins in South America, for example, to assess climate change impacts in the Amazon (Sorribas et al 2016), in hydrological and hydrodynamic modeling of rivers and lakes (Lopes et al 2018;Munar et al 2018;Fleischmann et al 2019aFleischmann et al , 2019b, in water management scenarios in transboundary river basins (Gorgoglione et al 2019), and in continental hydrological modeling for South America .…”

Use of large-scale hydrological models to predict dam break-related impacts

“…Finally, MGB-IPH for the case presented here was used based on an hourly discretization, similar to that observed in (Fleischmann et al, 2019a), which allows greater representativeness regarding the propagation of the estimated rupture hydrograph.…”